Vol 57, No 5 (2017)

Heterogeneous catalytic reactions of dimethyl ether (DME) with various compounds (alkenes, aromatic compounds, CO, etc.) are surveyed. Analysis of published data allows the conclusion that the formation of products generally involves surface intermediates produced by the interaction of DME with Brønsted acid sites. There is no formation of water in this case, suggesting that DME can be preferred to methanol in some cases. Surface intermediates CH*₃ which are bound to the oxygen atoms of the zeolite lattice (methoxides) and retain their reactivity in the case of temperature elevation to 473 K have been identified using IR, UV, and in situ high-resolution solid-state NMR spectroscopy. Based upon the data on the state of intermediates that are formed from DME on the surface of heterogeneous catalysts, a series of catalytic reactions involving DME, namely, methylation of alkenes and aromatic compounds, carbonylation, synthesis of ethanol, and partial oxidation resulting in a set of compounds have been considered. Some reactions, such as carbonylation of DME by synthesis gas, synthesis of ethanol, and synthesis of dimethoxymethane and polyoxymethylene dimethyl ether, are of industrial interest.

In Volga−Urals crude oils, an increase in the aromatics content is characterized by a rapid increase in the relative amount of polysubstituted aromatic rings and a generally lower proportion of bi- and polycyclic aromatics, unlike the case of Western Siberia oils. The difference between the oil and gas basins is most probably due to the special features of the source organic matter of the oils. The regional features of the Volga−Urals oils are a relatively weak relationship between the concentrations of mono- and bi- + polycyclic aromatics and a relatively close relation of Σn-Alk to typically uninformative parameter Hβ, which indicate a high uniformity of the composition of saturated cyclic compounds and moieties of hybrid naphthenoaromatic components. In addition, the assumption that (H/C)_ar/(H/C)_al = const does not hold for Volga−Urals oils. However, the relationships between the main parameters describing total aromaticity (primarily, C_ar, H_ar) and n-alkyl structures (primarily, Σn-Alk) are identical for oils from both the basins. The total number of relationships that can be universal for oils from different oil-and-gas basins is fifteen. To estimate C_ar from ¹H NMR data for Volga−Urals crude oils, a linear dependence on the two variables H_ar and H_α should be used. The expressions obtained to relate the structural-group parameters have made it possible to reveal a number of oils that stands out among the others.

The catalytic conversion of 4-tert-butylphenol (TBP) in hydrogen peroxide solutions in the presence of titanium oxide samples with different phase compositions and crystalline and amorphous titanosilicate samples has been studied. It has been shown that microporous crystalline titanosilicate TS-1 exhibits low activity in the TBP conversion owing to steric restrictions to the diffusion of the substrate molecules to catalytically active sites. The samples of titanium oxide compounds and mesoporous titanosilicates exhibit similar activity, while the selectivity of the latter for 4-tert-butylcatechol (TBC) is higher. The effect of the mesoporous titanosilicate concentration in the reaction mixture and the test temperature and duration on the TBP conversion and the TBC selectivity has been determined.

The catalytic properties of Inerton-supported nickel nanoparticles in benzene hydrogenation have been studied; rate constants of the reaction at different temperatures have been calculated. Activation energy and conversion have been determined, and the effect of size of nickel nanoparticles on their catalytic properties in benzene hydrogenation has been discussed.

Quantum chemistry and chemical thermodynamics methods have been used to calculate the energy characteristics of the direct alkylation reaction of benzene with ethane catalyzed by H-ZSM-5, an unmodified zeolite in the decationized form. It has been shown that the reaction of ethylbenzene synthesis from benzene and ethane with a small yield is thermodynamically feasible at temperatures below 400°C. The catalyst H-ZSM-5 significantly reduces the energy of the formation reaction of the benzyl and ethyl radicals.

The possibility for the synthesis of 5-chloro-2-hydroxybenzoic, 4-chloro-2-hydroxybenzoic, and 3-chloro-2-hydroxybenzoic acids via regioselective carboxylation of p-, m-, and o-chlorophenols, respectively, with sodium ethyl carbonate has been demonstrated. Simple and convenient procedures developed in this study for the synthesis of chlorohydroxybenzoic acids can be used for their preparative and industrial synthesis.

The cracking of С₁–С₄ associated petroleum gases to ethylene and propylene in the presence of electrically heated metal wires in a tubular quartz reactor in the temperature range of 300–600°С has been studied, while providing the heating by passing an electric current at a voltage of 25–40 V, a current intensity of 7.0–9.5 A, and a power of 200–350 W through a metal wire in the form of a tungsten, molybdenum, or nichrome coil contacting with the flowing gas stream. It has been found that the coil materials are arranged in the following order with respect to the alkene yield: tungsten > molybdenum > nichrome.

Water separated from crude oil and wastewater discharge from petroleum oil refineries contains significant quantity of dissolved hydrocarbons. Polycyclic aromatic hydrocarbons (PAHs) are major toxicants in wastewater of refineries. It is difficult to treat wastewater containing PAHs due to their recalcitrant property and low solubility. Conventional techniques for the treatment of wastewater are still a concern of toxicity. Electrochemical oxidation process has been found to be a favorable for treating wastewater. Electrodes with high stability and electrocatalytic activity are important factors for a successful electrochemical oxidation of toxic organics in wastewater. In this study titanium anodes were coated with tin, antimony and iridium oxide mixture from their respective salts by thermal decomposition method. FESEM and XRD used for surface characterization of Ti/SnO₂–Sb₂O₅–IrO₂ anode. Quantification of PAHs was done using GC–MS. Results confirm the presence of respective oxides on anode surface. Their electrocatalytic capability was tested for degradation of 16 priority PAHs in aqueous solution. Results reveal the complete degradation of naphthalene, acenaphthylene, acenaphthene and fluorene without using NaCl electrolyte. While in the presence of NaCl naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene were completely removed. About 98% of total PAHs removal was found at all initial pH values 3, 6, and 9 in the presence of electrolyte. Current study will be helpful in improving quality of petroleum industry wastewater containing PAHs.

Сommercial petroleum diesel, distilled biodiesel and jet fuel JP8 were used to prepare the new fuel blend with physicochemical properties meeting the petroleum diesel standards. The proposed fuel blend consisted of 75% (v/v) petroleum diesel, 20% (v/v) distilled biodiesel and 5% (v/v) jet fuel JP8. The humidity of the prepared fuel blend was regulated using the distilled biodiesel. The key physicochemical properties of fuel such as density, kinematic viscosity, conductivity and water content were measured using standard ASTM methods. The storage stability test for the studied samples showed that they remained unchanged even after 30 and 120 days from the preparation moment. The suggested fuel blend composition may be recommended for the industrial applications due to the benefits of adding 20% of the distilled biodiesel. The composition of the fuel blend meets the European directive which proposes adding up to 20% (v/v) of biodiesel to the petroleum based fuels.